1. Field of the Invention
The present invention relates to an image pick-up apparatus, and more particularly to an image pick-up apparatus having the capability of character recognition.
2. Description of the Related Art
There are various types of apparatuses having the capability of character recognition in which images of printed or handwritten characters are read first and then recognized as characters thereby converting them into machine-recognizable codes, wherein the resultant data may be processed further as required for specific purposes. One example of such an apparatus is a business card reader that reads characters representing a company name and personal name printed on a business card, converts the read characters into machine-recognizable codes, and transmits the resultant text data to an electronic tool such as a palmtop computer, an electronic address book, etc. Another example is a language translator. In this example, the translator reads foreign language sentences printed on paper via a scanner and performs character recognition on them thereby obtaining a series of character codes. The language translator then translates the foreign language sentences into Japanese sentences and prints or displays the result on paper or a monitor screen. There are also electronic systems capable of recognizing handwritten characters. For example, some systems read handwritten characters such as numeric characters filled in fields in a predetermined format such as a questionnaire, and recognizes them, wherein the resultant data may be subjected to further processing such as summing, retrieving, or statistical analysis. These apparatuses or systems treat printed or handwritten characters not as images but as characters (in the form of coded character data), which makes it possible to perform various processing that will be impossible if the image data is directly processed. That is, image data associated with characters is read via an image sensor and converted into text data by means of character recognition. This makes it possible to perform further complicated processing such as data compression, data retrieval, language translation, etc.
On the other hand, there are image pick-up apparatuses (video cameras) for recording and reproducing the image of a natural scene or subject, wherein the image is recorded in the form of image data. The image data output by this image pick-up apparatus can be input to a character recognition apparatus that converts the image data into text data and performs further processing such as that described above. The image pick-up apparatuses of this type are assumed to be used to take a picture of a natural scene or subject in a manner similar to that of conventional photographic cameras. Therefore, unlike scanners used on a desktop, they are designed to have basic capabilities and functions of a small size and light weight camera. When taking a picture of an object that cannot be moved, it is possible to take its picture by moving the image pick-up apparatus itself. It is also possible to perform adjustment regarding the size of a subject by adjusting the magnification by means of zooming or adjusting the distance to the subject. There is also provided an auxiliary illumination lamp that makes it possible to take a picture in the dark.
With the image pick-up apparatus of this type, it is possible to easily input image data of characters at a fixed location or characters having a size which could not be dealt with by other techniques. Thus, use of character recognition is expanded to a variety of applications.
In the technique described above, characters to be input are read first via an image pick-up apparatus or an image sensing unit, and the obtained image data is subjected to character recognition processing. The size of characters that can be recognized is limited by the resolution of the image sensing unit. This means that characters having a size less than a threshold cannot be recognized even if they look very clear.
In the case where an apparatus has an image sensing unit with no capability of adjusting the magnification, an operator can know the allowable lower limit of character sizes by referring to the description in an operation manual. In an apparatus having the capability of adjusting the magnification, in the case the characters are too small, a message indicating that the characters are too small to recognize is given at a stage of character recognition processing.
However, at a stage of acquiring a character image, an operator cannot know whether or not the character size is large enough for character recognition. If the size of the acquired character image is less than the allowable lower limit, the operator becomes aware of that fact when the image data is subjected to character recognition. Thus, there are disadvantages: (1) the operation becomes useless; and (2) it takes a long time to become aware of the failure.
There will be a further discussion below about a specific system in which image data of characters is acquired via an image sensing unit and then transferred to a separate character recognition apparatus which recognizes the characters thereby converting them into text data.
In the first step, characters to be recognized are captured by an image pick-up apparatus such that the images of the characters are focused on the screen of the view finder. At this stage, it is impossible to judge whether the characters to be recognized have a size large enough to be recognized. In this apparatus, it would be meaningless that an operation manual had a description about the allowable lower limit of character sizes because the ratio of the size of actual characters to that of character images can be changed by a zooming operation or by changing the distance to the subject. As a result, an operator has to input image data without any reference about the size. The character images acquired via the image sensing unit of the image pick-up apparatus are converted to image data by a signal processing unit and then transferred to the character recognition apparatus via input/output ports. Or otherwise, the converted image data is stored temporarily on a recording medium, and the recording medium is inserted into the character recognition apparatus thereby transferring the data. The character recognition apparatus attempts to recognize the input character image data. At this stage, it is judged whether the given characters have a proper size. If it is concluded that the size of the character is too small to be recognized, the apparatus issues a message to notify the operator of that fact. In response to the message, the operator should take required action. However, in any case, the operation and the time spent for that operation become useless, and thus every thing has to be done from the beginning. When an image containing information of a transitory phenomenon is dealt with, there may be no further chance, in the worst case, of acquiring an image of the same phenomenon.